1. Field of the Invention
This invention relates to a disc cartridge, and more particularly to a disc cartridge in which a disc medium such as a hard disc like an optical disc, a photomagnetic disc or a magnetic disc, a floppy disc, or the like is rotatably received.
2. Description of the Prior Art
Conventionally, a tray system or a cartridge system using a casing has been generally employed for protecting a floppy disc, a compact disc, a video disc or the like which is used for a digital-data storing unit, a video unit or the like from damage and dust to ensure its safety during its storage and operation. For this purpose, the casing is provided with a slidable shutter made of metal which is operated to close a pickup inserting hole and/or a drive shaft inserting hole of the casing in nonuse and open them in use.
Such a shutter is generally formed of a metal plate into a substantially U-shape. For this purpose, the metal plate is subjected to stamping and bending to make the shutter having a slider integrally formed. Unfortunately, this leads to waste of a metal material and renders manufacturing of the shutter highly troublesome. Also, the above-described construction of the so-formed therein conventional shutter causes shutter operating pin to strike against the shutter to wear and/or damage the pin, resulting in generation of dust such as metal powder and the like.
Assembling of the conventional shutter is often carried out by mounting the slider on a U-shaped shutter body by means of screws. However, this causes the number of parts to be highly increased, as well, as makes manufacturing of the shutter different due to the necessity of formation of a metal plate into the U-shaped shutter body by pressing and bending, so that operating efficiency and productivity of the shutter and therefore the disc cartridge may be extremely reduced.
In view of the foregoing, a shutter of a so-called three-part structure was proposed which comprises two shutter plate members and a slider connected to the shutter plate members through engagement between projections and recesses of the slider and the shutter plate members, as disclosed in Japanese Utility Model Application Laying-Open Publication No. 63879/1984, In the proposed shutter, assembling of the shutter and mounting of the shutter on a casing of a disc cartridge are carried out in a manner to mount the slider on the casing and then connect the shutter plate members to the slider. Alternatively, they are conducted by connecting the slider and shutter plate members together to form or assemble the shutter and then mounting the shutter on the casing.
However, for such assembling and mounting of the shutter, it is required to deform an end of each of the shutter plate members into a shape sufficient to permit it to be inserted under a holding plate of the casing in order to ensure smooth operation of the shutter, when it is needed to form each shutter plate member into an elongated shape as in an optical disc cartridge. Thus, assembling and mounting of the shutter are highly troublesome, resulting in the operating efficiency and productivity still being reduced.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of facilitating assembling of a shutter and mounting of the shutter on a casing to significantly improve its productivity.